MOT defect file
Shock absorber defective
Last updated
Quick answer
A damper is leaking or no longer controlling the spring. Replaced in pairs across an axle to keep handling balanced.
- Typical cost
- £180–£400
- DIY viability
- Possible with care
What you might notice
- The car bobbing for a second or two after a bump instead of settling in a single movement
- More nose-dive under braking and more squat under acceleration than the car used to have
- An oily film or a run of fluid down the body of the damper, often with road dirt stuck to it
- Cupped or scalloped wear across the tread, caused by the wheel skipping rather than staying planted
What causes it
- Wear of the internal seal and valving, which sets in gradually from somewhere around 60,000 to 80,000 miles
- A stone chip or corrosion pitting the piston rod, which then cuts the seal on every stroke
- A collapsed top mount or crumbled bump stop putting the damper out of line
- Overloading, regular towing, or a heavy pothole strike bending the rod
Advisory or failure?
Slight misting on the body of a damper is a minor defect and does not fail the car. A shock absorber that is leaking severely, obviously not damping, insecure, damaged or missing is a major defect. Where the condition is bad enough to compromise the vehicle's stability — a damper detached from its mounting, for instance — the grading is dangerous. Most testers assess this visually for leaks and security alongside a bounce test at each corner; where a suspension damping performance test is used instead, a difference of more than 30% between the two sides of an axle is also a major defect.
Can you fix it yourself?
Possible with care
Rear dampers on many cars are two bolts and a genuinely simple job. Front struts are not. The coil spring on a strut stores enough energy to kill, and releasing it needs proper matched spring compressors in good condition — the cheap hook-type clamps sold in bargain sets are exactly the ones that slip. Buying complete pre-assembled struts avoids handling the spring at all and is worth the extra. Dampers are replaced in pairs across an axle whichever route you take, or the car brakes and corners unevenly, and struts carry the camber setting so the alignment must be checked afterwards.
What it costs
A pair of rear dampers is £60 to £140 in parts with about an hour and a half of labour, landing near the bottom of the band. A pair of front struts is more like £120 to £250 in parts and two to three hours, plus alignment, which reaches the top. Complete strut assemblies cost more in parts but save enough labour to be the better value on many cars. Electronically adaptive dampers, fitted to many premium and performance models, sit well beyond this band — a single unit can cost more than a conventional pair.
What happens if you ignore it
Worn dampers lengthen stopping distances, because the tyres spend part of every bump lightly loaded or off the road entirely, and they undermine the ABS and stability systems that assume the wheels stay planted. The car becomes unpredictable in an emergency swerve, which is precisely when you need it not to be. In the meantime the uncontrolled movement chews through tyres and loads up the springs, top mounts and bushes around it.
This is general guidance, not a diagnosis. The severity DVSA records depends on the specific fault found, so the same item can appear as an advisory on one test and a failure on another. Ask a qualified tester or mechanic to inspect the vehicle.
Has this been recorded on your car?
Check the full MOT history for any UK registration.